Internal-combustion engine.



L. M. FOSTER INTERNAL COMBUSTION ENGINE. APPLICATION PILED JULY 8, 1911. 1,091,053. Patented Mar. 24, 1911 2 SHEETS-SHEET 1.

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L. M. FOSTER.

INTERNAL COMBUSTION ENGINE. APPLICATION FILED JULY 8, 1911.

1,09 1,053. Patented Mar. 24, 19m

2 SHEETS-SHEET 2.

1407x5815: 3] //v W s/v Tan M 5 3 E Z m /5WFM UNITED STATES, PATENT OFFICE.

LUCIAN M. FOSTER, OF NORWICH, NEW YORK.

INTERNAL-COMBUSTION ENGINE.

To all whom it may concern:

Be it known that I, LUCIAN M. FOSTER, of Norwich, in the county of Chenango, in the State of New York, have invented new and useful Improvements in Internal-Combustion Engines, of which the following, taken in connection with the accompanying drawings, is a full, clear, and'exact de scription.

This invention relates to certain improvements in internal combustion engines preferably of the fohr-cycle motor vehicle type and refers more particularly to certain connections between the piston rod and pitman for imparting rotary motion to the crank shaft of the engine.

The main object is to increase the working power and efliciency of this type of engine or rather to reduce the loss of power caused by compression of the explosive mixture, inefficient cleansing of the cylinder from spent gases and excessive shock or vibration of the engine and support upon which it is mounted. In other words I have sought to obviate the loss of power and inefiiciency of this class of engines by establishing a resilient differential leverage connection between man by which the power required to compress the charge of explosive mixture is given back to the propulsion of the crank shaft.

Another object of this resilient connection is to enable the piston to adjust itself automatically to varying volumes of explosive mixture under compression so that the heavier charges, as, for example, under low speed of the engine will be subjected to greater pressure for producing a higher power of efiiciency than a lighter charge, as, for example, under higher speed when the power is increased by the momentum.

A still further object is to provide means separate from the cylinder for guiding the piston axially in its reciprocatory movement against diagonal thrusts resulting from direct connection of the pitman to the piston. The effect, therefore, is greater economy in fuel, less shock or vibration of the engine or vehicle upon which it is mounted, reduced wear upon the piston and cylinder, and increased power efiiciency.

Other objects and uses will be brought out in the following description.

In the drawings-Figures 1, 2 and 3 are similar longitudinal vertical sectional views v Specification of Letters Patent.

Application filed July 8, 1911.

the piston rod and pit Patented Mar. 24, 1914.

Serial No. 637,505.

of an internal combustion engine embodylng the various features of my invention but showing the piston and connections between it and the pitman in different positions. F 1g. 4 is a longitudinal vertical sectional view of a portion of the same engine taken on line 44 Fig. 1. Fig. 5 is a transverse sectional view taken on line 5-5 Fig. 4.

The engine illustrated is of the four-cycle type having a cylinder 1 supported upon a suitable base or frame 2 and provided with a suitable inlet -3- and exhaust -4 and spark plug 5-, the inlet for the explosive mixture and exhaust for spent gases being controlled by valves 6 and 7 which are operated in the usual manner for this type of engine, said cylinder being also provided with suit-able cooling means as a chamber 8 in which water or other cooling liquid may be circulated in any well known manner.

Movable in the cylinder is a reciprocatory piston 9- having a piston rod 10- connected to a cross head 11- which is guided in ways -12- in the sides of the frame 2- so as to guide the piston in a straight line in its reciprocatory movement, thereby obviating any liability of angular thrust and incidental friction and wear to the piston and cylinder arising therefrom as when the piston is connected directly to the pitman.

The cross head preferably consists of opposite parallel arms spaced some distance apart and united at their inner ends for connection with the pistonrod --10, the intermediate portions of said arms being connected by a cross bar or bearing plate -13- for receiving and supporting one end of a coil spring 14 and also serving as a bearing for a rock arm hereinafter described.

Mounted upon the lower or outer end of theframe 2 is a crank shaft 15- to' which is connectedone end of a pitman 16. Journaled upon the opposite or inner end of the pitman is a rocker arm 17 having a curved upper or inner bearing face -18- in rolling contact with the under or outer face of the bearing plate 13-, thereby constituting a variable leverage connection betweenth'ecross head and pitman for a purpose hereinafter described.

The rock arm -17 is provided with ears or lugs 19 projecting inwardly or upwardly through an opening 20- in the plate 13- to which is pivoted at 2l one end of a spring tensloning rod or bolt 22, the opposite or upper end of said rod or bolt being preferably screwthreaded and provided with an adjustable head or nut 23-- engaging the adjacent or upper end of the spring l& for holding the latter under compression and thereby holding the rock arm 17 in contact with the underside of the plate -13. The rock arm 17 is therefore spring pressed against the bearing plate 13 and con stitutes a variable leverage connection between the cross head and pitman, while the spring 22 constitutes a resilient connection between the cross head and rock arm so that the spring together with the rock arm affords what may be termed a resilient variable leverage connection between the cross head and pitman.

It will be observed that the greater portion of the spring 14 and also the connections between the rock arm 17 and spring are located at one side of the roduced axis of the piston and cross head and that the normal point of contact between the rock arm and bearing plate 13- is also some distance to the same side of said axis when the piston is at the extreme limitof its exhaust stroke for cleansing the cylinder 0r expelling the spent gases through the exhaust port at which time the spring is under minimum tension as shown in Fig. 1 ready to begin its down stroke for drawing in a maximum charge of the explosive mixture, the spring 14 being ofsufiicient tension to hold the plate -13- in contact with the rock arm l7 during the suction stroke of the piston so as to cause this stroke of the piston to be substantially equal to double the throw of the crank shaft.

When the piston is at the extreme limit of its exhaust stroke as above described, the spring tensioning rod -22- is substantially parallel with the axis of the piston and the point of contact between the rock arm 17- and bearing plate '13 is substantially coincident with the center of the draw rod and the lug -19 is also substantially parallel with said rod so that the maximum leverage of the connection between the bearing plate 13- and pitman is substantially equal to the distance between the produced axis of the piston and a line drawn from the point of cont-act and through the center of the draw rod parallel with said axis.

Assuming now that the crank shaft is rotating in the direction indicated by arrow X the piston will be drawn downwardly from the position shown in Fig. l and the inlet valve 6 opened to draw in a charge of the explosive mixture, the spring 14 being sufliciently stiff to effect this result without changing the point of contact between the rock arm 17 and bearing plate 13. Now, as the crank shaft continues its complete revolution thereby advancing the piston to compress the charge, the resistance to further compression gradually increases until it is sufficient to overcome the tension of the spring 14 at which time the piston will have assumed approximately the position shown in Fig. 2, thereby causing the bearing plate 13- to hold the rock arm 17- against further inward movement while the pitman continues to move through the limit of its inward movement, thereby rocking the arm -17 against the bearing plate 13 and causing the point of contact to shift toward the polnt of connection of said rock arm with the pitman and causing the point of connection between the rock arm and draw rod 22- to be drawn outwardly and downwardly to increase the tension of the spring. The point of contact between the rock arm -17 and bearing plate 13 therefore constitutes the fulcrum of the rock arm with the power applied at the point of connection with the pitman, while the load of comprcssing the spring is applied to the outer end of the arm, and by connecting the rock arm 17- to the draw rod 22 at a point above the line of contact between said arm and plate 13-, it is evident that as the arm is rocked from its initial position, the point of connection with the draw bar will be quickly thrown outwardly and downwardly, thereby increasing the distance between said point of connection and fulcrum or point of contact between the plate l3 and rock arm and at the same time dimin ishing the distance between such point of contact and point of application of the power and this will continue until the load equals the power, this condition depending somewhat upon the curvature of the rock arm which determines the compression space between the piston and head of the cylinder. In other words, during the compression of the mixture, the point of contact between the rock arm 17 and bearing plate -13 will gradually shift from its initial position until the power and load applied to the rock arm at opposite sides of the point of contact will balance each other and thereby determine the amount of compression space for the explosive charge ready for firing as shown in Fig. 2. Under these conditions it is evident that the compression stroke of the piston is less than its exhaust stroke or throw of the crank shaft and that the spring is under compression and operates to give back the power stored therein to the crank shaft as soon as the pitman is moved by the dead center.

Now, as the explosive mixture is fired its expansive force instantly drives the piston together with the cross head and bearing plate 13 downwardly with greater power than that of the previously compressed spring tending to oppose such action, thereby further depressing the rock arm 17 and shifting the contact point between said rock arm and contact plate 13 nearer to the point of connection of said rock arm with the pitman and thus additionally compressing the spring 1-1 but with gradually reducing force until such resistance and power tending to compress the spring is again balanced under which con ditions the piston assumes approximately the position shown in Fig. 3 at which time the pitman will have passed some distance beyond its dead center and will be acted upon by the combined forces of the power afforded in the spring and expansive force of the fired mixture, all of which forces will be applied to the rotation of the crank shaft as it continues from its dead center on the compression stroke when the turning force is most effective. As soon as these forces are spent which will occur as the piston reaches the limit of its down-stroke, the spring --14- and rock arm -17 will have returned to their normal positions with the point of contact between the bearing -13 and rock arm substantially coincident with the longitudinal center of the draw bar -22 and spring so that on the upstroke of the piston during which the exhaust valve 17 is opened, the spent gases will be effectively expelled from the cylinder and the piston returned to its initial position as shown in Fig. 1, thereby effecting a complete exhaust of all of the vitiated gases ready to take in another charge of unadulterated mixture after which the operation previously described is repeated.

It is now clear from the foregoing description that during the compression stroke of the piston, the degree of compression of the spring and compression space will de pend somewhat upon the quantity of explosive mixture admitted to the cylinder as controlled by the usual throttle-and that in like manner under firing of the explosive mixture, the further degree of compression of the spring will depend somewhat upon the amount of the explosive charge but under all conditions, either under the compression or firing stroke, the force applied to the pitman and crank shaft while practically instantaneous is gradual, thereby relieving the engine and carriage orother support upon which it is mounted from excessive shock or vibration, and while a certain amount of resistance to the action of the crank shaft on the compression stroke is necessarily introduced, a considerable part of this resisting power is given back by the spring in the propulsion of the shaft. Another im ortant advantage, however, is the ability 0 the engine to provide ample compression space for the compression of the explosive mixture and at the same time to allow the piston to travel to the extreme inner end of the cylinder for positively expelling all of the spent gases and thereby permitting the inlet of an unadulterated mixture which necessarily gives an increased power efliciency and reliability to the engine.

One advantage of having the spring ec centric to the piston is that it brings the connection between the center of the spring and cam 17 at one side of the longitudinal center of the connecting rod 16- when the latter is in a vertical osition so that immediately upon the explosion and second com- Eression of the spring, such spring gives ack its power to the connecting rod and crank arm just after the connection between the connecting rod and crank arm passes the dead center in the direction of movement of the arrow when this increased power is most needed in driving the crank arm through the succeeding quarter turn. Another advantage is that it enables the spring to be brought wholly outside of the cylinder away from the heat.

\Vhat I claim is:

1. In an internal combustion engine, a cylinder, a piston, a piston rod and a cross head secured to the rod, a bearing plate on the cross head, a spring bearin against the inner side of the plate, and w olly outside of the cylinder, a bearing member for the opposite end of the spring movable relatively to said plate, a crank shaft and a pitman thereon, a rock arm on the pitman, and connections between said rock arm and bearing member, said rock arm being engaged with the outer side of said plate.

2. In an internal combustion engine, a cylinder, a piston, a cross head, connect-ions between the piston and cross head, and wholly outside of the cylinder, a bearing plate on the cross head, a crank shaft and a pitman thereon, and a rock arm on the crank shaft in rolling contact with and spring pressed against said plate.

3. In an internal combustion engine, a cylinder, a piston, a bearing plate, connections between the piston and bearing plate for reciprocating the latter, a crank shaft and pitman thereon, a rock arm on the pit-v man in rolling contact with the outer surface of the plate, a rod pivotally connected to the rock arm at a oint inside of its line of contact with said plate and provided with a head, and a coil spring external to the cylinder-and interposed between said head and late.

4. 11 an internal combustion engine, a cylinder, a piston, a bearing plate, connec" tions between the iston and bearing plate for reciprocating t e latter, a crank shaft and pitman thereon, a rock arm on the pitman having a curved bearing face in rolling contact with said plate, and resilient means external to the cylinder for holding said plate and rock arm in contact.

5. In an internal combustion engine, a cylinder, a piston, a cross head, connections between the cross head and piston, a bearing plate on the cross head, a coil spring wholly external to the cylinder having one end seated on the plate, a crank shaft having a pitman, a rock arm having a curved face in rolling contact with said plate, an car on the rock arm extending through an opening in said plate, a rod pivotally connected to said ear, and a head on the rod engaged with the opposite end of the spring.

6. In an internal combustion engine, a cylinder, a piston, a crank-shaft and a pitman thereon, a bearing member connected to the piston, a rock-arm on the pitman in rolling contact with said member, a spring wholly external to the cylinder for maintaining such contact, and means actuated by said rock-arm for increasing the tension of said spring as the point of contact between the rock-arm and bearing member shifts toward the axis of the rock-arm.

7. In an internal combustion engine, a cylinder, a piston, a bearing member, rod connections between the piston and bearing member, a crank shaft, a pitman on the crank shaft, a rock arm on the pitman having a curved bearing face in rolling contact with the bearing member, a draw rod connected to the rock arm at a point inside of the line of contact between the rock arm and bearing member, a head on the draw rod, and a spring interposed between the head and bearing member external to the cylinder for holding the rock arm in con tact with said member.

8. In an internal combustion engine, a cylinder, a piston, a bearing plate, connections between the bearing plate and piston, a coil spring wholly outside of the cylinder away from the heat and having one end seated on the plate, a crank shaft having a pitman, a rock arm having a curved face in rolling contact with said plate, a projection on the rock arm extending through an opening in said plate, and connections between said projection and spring.

In Witness whereof I have hereunto set my hand on this 29th day of June 1911.

LUCIAN M. FOSTER.

Witnesses:

H. E. CHASE, E. F. SPEAKING. 

